WEIGHT loss jabs could interfere with vital scans, potentially leading to cancer misdiagnosis, scientists say.
Whether they’re taken for diabetes or weight loss, through the NHS or privately, the use of jabs like Ozempic, Wegovy and Mounjaro is becoming more widespread.
Weight loss jabs may affect how tissue shows up on scans used to detect and stage cancer[/caption]
In the UK, an estimated 1.5 million people are thought to be on weight loss injections.
Now, British researchers say the jabs, may affect how tissue shows up on scans used to detect and stage cancer – known as PET-CT scans.
As a result, healthy tissue could be misinterpreted as potentially cancerous if a patient’s medication history isn’t also taken to account.
It means patients on weight loss jabs – known as Glucagon-like peptide-1 receptor agonists or GLP-1s – may be subjected to unnecessary further testing, as well as stress, uncertainty and delays in treatment for other conditions.
Dr Peter Strouhal, medical director at Alliance Medical – which provides diagnostic imaging services in the UK – who lead the study, said: “We noticed unusual uptake in one of our patients on a GLP-1 agonist, which prompted a wider review across our network.
“We found that these altered patterns are increasingly common, yet there is currently no national or international guidance in the UK addressing this emerging issue.”
The research was presented at the Annual Congress of the European Association of Nuclear Medicine in Barcelona.
After noticing something “unusual” in one patient’s scan, researchers reviewed the scans PET-CT of several patients taking weight loss medication.
A PET-CT scan combines a CT scan and a PET scan to give detailed information about tumours.
It uses a mildly radioactive liquid, called radioactive tracer, to show areas of your body where cells are more active than normal.
A higher level of metabolic activity – and concentration of tracer on the scan – could signal potentially cancerous activity, which appears as brighter spots.
The researchers found “several” patterns of tracer on the scans among GLP-1 users that were “atypical’ and “could be misinterpreted” as potentially cancerous areas.
Areas with high levels of tracer don’t always signal cancer and could be a sign of other conditions such as infections or inflammation.
Dr Strouhal said: “Recognising the characteristic uptake associated with GLP-1 agonists helps avoid unnecessary anxiety and interventions, ensuring patients receive the right care, at the right time, without detours or doubt.”
Researchers stressed they didn’t recommend that people stop taking weight loss jabs before scans or that patients be prepared for them any differently.
They said further research involving more data is needed in order to show that GLP-1s actually interfere with the interpretation of PET-CT scans.
Only then can recommendations for weight loss jab users be changed.
Instead, researchers advised that imaging teams carefully document patients’ medication histories so that they take it into account when interpreting scans.
Current UK guidelines do not address this issue, but Australian guidance suggests continuing treatment with GLP-1s, fasting from midnight before the scan and scheduling the test for the morning.
Researchers intend to collect data from other imaging centres to provide a stronger evidence base for future national guidance.
Weight loss jabs have previously been linked to a reduced risk of cancer.
In August, researchers from the Indiana University School of Medicine found GLP-1s like Ozempic and Mounjaro reduced the overall chances of the disease by 17 per cent in overweight and obese patients
The decreased risk was strongest for ovarian, womb and certain brain tumours.
But researchers couldn’t specify whether the change in cancer risk was due to the jabs themselves or drug-induced weight loss.
Meanwhile, scientists from the University of Michigan said Mounjaro – dubbed the ‘King Kong’ of weight loss jabs – may help slow the growth of breast cancer tumours.
